TY - JOUR A1 - Braune, Steffen A1 - Gross, M. A1 - Walter, M. A1 - Zhou, Shengqiang A1 - Dietze, Siegfried A1 - Rutschow, S. A1 - Lendlein, Andreas A1 - Tschoepe, C. A1 - Jung, Friedrich T1 - Adhesion and activation of platelets from subjects with coronary artery disease and apparently healthy individuals on biomaterials JF - Journal of biomedical materials research : an official journal of the Society for Biomaterials, the Japanese Society for Biomaterials; the Australian Society for Biomaterials N2 - On the basis of the clinical studies in patients with coronary artery disease (CAD) presenting an increased percentage of activated platelets, we hypothesized that hemocompatibility testing utilizing platelets from healthy individuals may result in an underestimation of the materials' thrombogenicity. Therefore, we investigated the interaction of polymer-based biomaterials with platelets from CAD patients in comparison to platelets from apparently healthy individuals. In vitro static thrombogenicity tests revealed that adherent platelet densities and total platelet covered areas were significantly increased for the low (polydimethylsiloxane, PDMS) and medium (Collagen) thrombogenic surfaces in the CAD group compared to the healthy subjects group. The area per single platelet—indicating the spreading and activation of the platelets—was markedly increased on PDMS treated with PRP from CAD subjects. This could not be observed for collagen or polytetrafluoroethylene (PTFE). For the latter material, platelet adhesion and surface coverage did not differ between the two groups. Irrespective of the substrate, the variability of these parameters was increased for CAD patients compared to healthy subjects. This indicates a higher reactivity of platelets from CAD patients compared to the healthy individuals. Our results revealed, for the first time, that utilizing platelets from apparently healthy donors bears the risk of underestimating the thrombogenicity of polymer-based biomaterials. KW - platelets KW - biomaterials KW - hemocompatibility KW - cardiovascular disease KW - cardiovascular implant Y1 - 2016 U6 - https://doi.org/10.1002/jbm.b.33366 SN - 1552-4973 SN - 1552-4981 VL - 104 SP - 210 EP - 217 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Braune, Steffen A1 - Walter, M. A1 - Schulze, F. A1 - Lendlein, Andreas A1 - Jung, Friedrich T1 - Changes in platelet morphology and function during 24 hours of storage JF - Clinical hemorheology and microcirculation : blood flow and vessels N2 - For in vitro studies assessing the interaction of platelets with implant materials, common and standardized protocols for the preparation of platelet rich plasma (PRP) are lacking, which may lead to non-matching results due to the diversity of applied protocols. Particularly, the aging of platelets during prolonged preparation and storage times is discussed to lead to an underestimation of the material thrombogenicity. Here, we study the influence of whole blood-and PRP-storage times on changes in platelet morphology and function. Whole blood PFA100 closure times increased after stimulation with collagen/ADP and collagen/epinephrine. Twenty four hours after blood collection, both parameters were prolonged pathologically above the upper limit of the reference range. Numbers of circulating platelets, measured in PRP, decreased after four hours, but no longer after twenty four hours. Mean platelet volumes (MPV) and platelet large cell ratios (P-LCR, 12 fL - 40 fL) decreased over time. Immediately after blood collection, no debris or platelet aggregates could be visualized microscopically. After four hours, first debris and very small aggregates occurred. After 24 hours, platelet aggregates and also debris progressively increased. In accordance to this, the CASY system revealed an increase of platelet aggregates (up to 90 mu m diameter)with increasing storage time. The percentage of CD62P positive platelets and PF4 increased significantly with storage time in resting PRP. When soluble ADP was added to stored PRP samples, the number of activatable platelets decreased significantly over storage time. The present study reveals the importance of a consequent standardization in the preparation of WB and PRP. Platelet morphology and function, particularly platelet reactivity to adherent or soluble agonists in their surrounding milieu, changed rapidly outside the vascular system. This knowledge is of crucial interest, particularly in the field of biomaterial development for cardiovascular applications, and may help to define common standards in the in vitro hemocompatibility testing of biomaterials. KW - Platelet KW - platelet function KW - platelet rich plasma KW - whole blood KW - platelet aging KW - platelet storage KW - hemocompatibility KW - biomaterials Y1 - 2014 U6 - https://doi.org/10.3233/CH-141876 SN - 1386-0291 SN - 1875-8622 VL - 58 IS - 1 SP - 159 EP - 170 PB - IOS Press CY - Amsterdam ER - TY - JOUR A1 - Lange, Maik A1 - Braune, Steffen A1 - Luetzow, Karola A1 - Richau, Klaus A1 - Scharnagl, Nico A1 - Weinhart, Marie A1 - Neffe, Axel T. A1 - Jung, Friedrich A1 - Haag, Rainer A1 - Lendlein, Andreas T1 - Surface functionalization of poly(ether imide) membranes with linear, methylated oligoglycerols for reducing thrombogenicity JF - Macromolecular rapid communications N2 - Materials for biomedical applications are often chosen for their bulk properties. Other requirements such as a hemocompatible surface shall be fulfilled by suitable chemical functionalization. Here we show, that linear, side-chain methylated oligoglycerols (OGMe) are more stable to oxidation than oligo(ethylene glycol) (OEG). Poly(ether imide) (PEI) membranes functionalized with OGMes perform at least as good as, and partially better than, OEG functionalized PEI membranes in view of protein resistance as well as thrombocyte adhesion and activation. Therefore, OGMes are highly potent surface functionalizing molecules for improving the hemocompatibility of polymers. KW - hemocompatibility KW - poly(ethylene glycol) KW - polyglycerol KW - polyimides KW - surface chemistry Y1 - 2012 U6 - https://doi.org/10.1002/marc.201200426 SN - 1022-1336 VL - 33 IS - 17 SP - 1487 EP - 1492 PB - Wiley-VCH CY - Weinheim ER -